The operating fluid used in these chillers may be
either a CFC or HCFC type refrigerant. Currently eighty
to ninety percent of centrifugal chillers use CFC-11 or
CFC-12 refrigerants, the manufacture and use of which
is being eliminated under the terms of the Montreal Protocol.
New refrigerants HCFC-123 and HCFC-134a are
being used to replace the CFC refrigerants but refriger-